Receive and clean
Sieves, magnets and destoner. Aflatoxin check per lot before unloading: it is the only moment you can still reject.
Flours
Precooked corn flour
The entire difference between a flour that forms dough in cold water and one that crumbles comes down to a single phenomenon: how much starch gelatinised during cooking. Neither the mill nor the packaging fixes it afterwards.
Control parameters
| Variable | Value | Why |
|---|---|---|
| Raw material | White or yellow maize | Clean, dry grain with no fungal damage. Damp or aflatoxin-bearing maize contaminates the whole batch and no process corrects it. |
| Degerming | Remove germ and pericarp | The germ carries the fat that goes rancid. Leave it in and the flour lasts weeks instead of months. |
| Cooking | 85 – 95 °C with steam | This is where the starch gelatinises. The step that turns raw flour into precooked flour. |
| Cooking moisture | 45 – 50 % | Without enough water the starch granule does not swell and gelatinisation stays partial. |
| Flaking | Rollers | Flattens the cooked grain and exposes surface: speeds drying and evens out texture. |
| Drying | Down to 8 – 13 % moisture | Below 13 % the product is stable; above it, it cakes and moulds. |
| Milling and sizing | 40 – 60 mesh | Particle size defines how the dough feels. Too fine turns sticky; too coarse feels gritty. |
Process
Step by step, with the temperatures.
Condition and degerm
Lightly moisten to loosen the pericarp, then separate germ and bran. This also yields a saleable by-product for animal feed.
Cook
Steam at 85 – 95 °C for 20 to 40 minutes depending on equipment. The variable you measure is not time, it is degree of gelatinisation.
Flake
Rollers flatten the cooked grain into flakes.
Dry
Hot air down to 8 – 13 % moisture. Drying too fast cracks the flake and raises the fines fraction.
Mill and classify
Milling and sieving to target particle size. Out-of-spec fines are reprocessed, not discarded.
Fortify and pack
Add the vitamin and iron premix your national regulation requires, and pack with a moisture barrier.
| Control point | Value |
|---|---|
| Water absorption index (WAI) | 4 – 6 g water per g flour |
| Final moisture | 8 – 13 % |
| Typical particle size | Through 40 – 60 mesh |
| Yield from grain | 70 – 75 % |
| Shelf life | 6 – 12 months depending on packaging |
| Fortification | Vitamin A, B1, B2, niacin and iron, per national rule |
Troubleshooting
What went wrong, and why.
Half the craft is reading the defect. These are the ones that keep coming back.
| What you see | What caused it |
|---|---|
| Dough will not bind, it crumbles | Incomplete gelatinisation: short cooking, low temperature or too little moisture. The most frequent defect and the most expensive. |
| Sticky, hard-to-handle dough | Milled too fine or over-gelatinised. The flour takes up more water than the user expects. |
| Rancid taste after two months | Germ was left in. Its fat oxidises and drags the whole product with it. |
| Caking in the bag | Final moisture above 13 % or packaging without a barrier. In tropical climates this happens within weeks. |
| Greyish colour | Excess drying temperature or poorly separated pericarp. |
Frequently asked
What people ask before they start.
How is it different from ordinary corn flour?
Ordinary corn flour is raw ground maize: it has to be cooked to be eaten. Precooked flour has already been gelatinised, so it hydrates and forms dough cold in minutes. All the added value sits in that step — and that is also where it is lost when the process is not controlled.
Which variable must I measure without fail?
The water absorption index. It predicts how the dough will behave in the consumer’s hands and is measured in the lab with simple equipment. A plant that does not measure it is manufacturing blind and only finds out when product comes back.
Can it be made with yellow maize?
Yes, and in several markets that is the norm. Colour and flavour shift slightly, and yellow brings carotenes. Technically the process is identical; what changes is each country’s consumer expectation.
Contact
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